This invention relates to structural glass units and in particular to structural glass units comprising a multi-ply glass assembly, such as a glass laminate or double glazing unit, which is used in a situation, for example as part of a roof structure, where it is desirable to secure the structural glass unit against a bending moment.
It is known to secure a glass laminate to a supporting structure by means of bolts which extend through aligned holes in the glass sheets of the laminate and the plastics interlayer material. GB 1 272 774 describes such a laminated structure for use as an aircraft window. There is also in U.S. Pat. No. 4,204,374 a description of an aircraft windshield which is bolted to the airframe structure.
GB 2,148,372 A describes a glass assembly comprising a planar array of sealed multiple glazing units which are secured to supporting members by mechanical fixings which pass through the outer sheets of the units outside the seals of those units. The outer sheets are sealed edge-to-edge.
When using laminated glass units in architectural structures it has been found that if the edge of a laminate is gripped sufficiently tightly to support the edge of the laminate against a bending moment, the pressure on the interlayer of plastics material causes the interlayer to exude from the laminate. It has also been found that if the edge of a sealed multiple glazing unit is gripped too tightly the pressure may cause deformation of the spacer strip, usually an aluminium spacer and of the sealant which is used to seal the spacer strip between the panes of the glazing unit.
This invention is based on the discovery that this problem can be overcome and a more secure load bearing connection can be achieved by securing the multi-ply glass assembly by connection to one glass sheet only of the assembly.